Abstract: A pot experiment was conducted to study the effects of inoculation with arbuscular mycorrhizal (AM) fungi Glomus versiforme (G.v), G. mosseae (G.m), G. intraradices (G.i), G. aggregatum (G.a), and G. etunicatum (G.e) on the mycorrhizal colonization, growth, and zinc and phosphorus contents as well as some physiological indices in leaves and roots of trifoliate orange (Poncirus trifoliata (L.) Raf.) seedlings under zinc contamination. In zinc-contaminated soil, inoculation with G.i, G.e, or G.m increased the seedlings biomass significantly. The mycorrhizal colonization and mycorrhizal dependency were the highest with G.i inoculation, followed by G.e and G.v inoculation. Inoculation with AM fungi significantly decreased the shoot zinc content, and promoted the zinc accumulation in roots (except for G.a). The shoot/root ratio of zinc translocation coefficient was the lowest in treatment G.i, second lowest in treatment G.e, and the highest in treatment G.v. AM fungi inoculation increased the phosphorus content in roots significantly, and G.i inoculation also significantly increased the phosphorus content in shoots. Inoculation with G.i or G.e significantly decreased the MDA contents in leaves and increased the CAT activity and proline content in roots, but had little effects on the POD activity in roots, compared with the control. Our study showed that G.i inoculation was most beneficial to the tolerance of trifoliate orange against zinc contamination, followed by G.e, and G.v  inoculation.

Key words: Coastal areas of Southeast China, Alexandrium sp., Cysts, Distribution, Germination